Garlic growing at MOFGA's Common Ground Education Center in Unity. English photo.

By Tom Vigue

People usually say mid-October is about the right time to plant garlic in central Maine. That rule of thumb will, in most years, produce a decent crop.

But why are more or fewer cloves per bulb sometimes produced, or more double cloves? Why is storage life better some years than others? Why do some harvested bulbs weigh more or less (even if they are of normal size) than others?

Knowing some of garlic’s quirks helps answer these questions.

Here’s an example. ‘Georgian Fire,’ a Porcelain type garlic, most often has four very large cloves per bulb, but a friend’s ‘Georgian Fire’ was producing six or so cloves per bulb and the bulbs were not as hard as expected, nor as long keeping. At the same time my own had devolved into producing an average of three cloves per bulb. Some had only two! They were very hard and kept longer than usual – but only two cloves? That’s very discouraging for propagation. And in the kitchen one rarely wants a clove that big.

It turns out, temperature and time of planting were at play.

Garlic performs best if the planting stock is exposed to temperatures between 43 and 50 F for about two weeks before planting. Stock that has not experienced enough cold before planting will produce bulbs with more but smaller cloves and with an increased tendency to double cloves (two cloves joined together). Such bulbs, though significantly larger, will likely weigh less and have looser skins than those from properly chilled stock, resulting in shorter storage life.

On the other hand, planting stock exposed to a lot of time at temperatures in the 30s will produce bulbs that will be on average significantly smaller with many fewer cloves and almost no tendency to double cloves. Such bulbs will be denser and heavier, with a longer storage life. But only two huge cloves per bulb is just too discouraging. Something between these extremes is ideal.

My friend, I learned, stored her planting stock indoors until planting time, so it was not exposed to cold. Storing the stock in a woodshed or similar cold structure would help.

My own stock was stored in a woodshed. For a few seasons, circumstances had me planting late, so the stock was exposed to many frosty nights before planting. Moving the stock indoors after judging that it had experienced enough cold was the solution. Moving cloves indoors will not negate the benefit the cold already had on the stock.

The second issue is the date of planting. Garlic does best when planted about four weeks before the ground freezes, because root growth begins in the fall. A critical humidity, provided by soil moisture, induces root growth. That humidity usually occurs one to two weeks after planting, when roots will grow for a couple of weeks more before soils freeze.

The importance of fall root growth cannot be overstated. Since some root growth always precedes sprouting and leaf growth, garlic that failed to grow roots in the fall will emerge and begin leaf growth later in the spring. Maximum leaf growth, which directly affects maximum bulb size, occurs by summer solstice, so any loss of growing days before solstice means correspondingly smaller bulbs.

Although some root growth is needed before sprouting can begin, planting too early in the fall could induce leaf sprouting then. A little sprouting is probably okay, but if sprouts emerge from the soil, an abrupt, severe cold snap could injure them.

Getting the timing right is rather a crapshoot. Who knows when the ground will freeze this year, or next year, or any year? All we can do is try our best. At least we will understand what is going on when we get it right (or wrong).

A few other details influence garlic growth. Planting cloves from smaller bulbs will result in smaller, weaker plants and consequently smaller harvested bulbs. But planting the largest cloves from the largest bulbs will result in the greatest lack of uniformity in the size of harvested bulbs. Cloves from medium to medium-large bulbs make the best planting stock. Interestingly, the size of the seed bulb is many times more significant than the size of the seed clove in determining the eventual size of harvested bulbs.

Also, planting double cloves does not influence the frequency of double cloves in the harvested bulbs. Double cloves will, of course, result in pairs of bulbs growing together that will be asymmetrical but will not necessarily contain double cloves. Formation of double cloves is determined by the temperature considerations discussed above and the choice of cultivar. Some cultivars tend to have double cloves; in others doubles are rare to nonexistent.

When planting, push cloves 3 to 4 inches deep into nicely tilled and heavily composted soil. They should be covered, but the soil needn’t be firmed over them. Then cover with 6 to 8 inches of mulch. Rain, snow, ice, etc., will pack the mulch to half that thickness, or less. Mulch moderates temperature fluctuations, preventing the alternate freezing and thawing that can heave cloves out of the ground. It also conserves moisture (humidity), which is needed to initiate root growth; and it controls weeds.

Garlic’s very strong sprout can easily emerge through a thick mulch in spring, if the mulch was loose and fluffy when applied. Avoid whole leaves, as they mat too densely for sprouts to penetrate. Well-shredded leaves are fine. Straw is said to be best, but fluffed hay is fine. Fresh mowings are fine if they are coarse and fluffy. Avoid fine lawn clippings as they mat densely.

For more information, read Growing Great Garlic by Ron L. Engeland.

About the author: Tom Vigue practices veganic farming at his and Eileen Fingerman’s Kiwi Hill Farm in Sidney, Maine.